1. Field of the Invention
The present invention relates to a vehicle lamp, and in particular to forming a mark on an inner surface of a front lens made of synthetic resin, and its marking method.
2. Description of the Related Art
Recently, a front lens made of synthetic resin has been adopted in various vehicle lamp. FIG. 10 depicts an inner surface of a front lens 2 having various marks formed thereon such as a lamp certification mark M1, a lamp center display mark M2, a trade mark M3, a lamp identification mark M4, and the like. These marks were conventionally formed by providing a carved seal on a mold for forming the front lens 2. However, there are cases in which the display content of some marks must change, even for front lenses having the same shape. For example, regarding the lamp certification mark M1, the displayed content of the mark must be changed according to the destination of the lamp (the export country of a vehicle on which the lamp is mounted).
Therefore, for a mark in which the displayed content must be changed, typically a removable insert was prepared for each variation (for example, regarding the lamp certification mark M1, a removable insert was set for each destination), whereby a front lens having the mark of which displayed contents are different was formed with a common mold.
However, in cases where a removable insert is used in order to accommodate changes of the mark displayed content, there is a problem that the outline of the removable insert inevitably appears on the inner surface of front lens. Particularly, in case that the front lens is a transparent lens or a lens similar to the transparent lens, an outline 4 of the removable insert appears conspicuously on the inner surface of the front lens 2, as shown in FIG. 10. Therefore, there is a problem that the appearance of the lamp is deteriorated. The problem also occurs if the mark is formed on an outer surface of the front lens.
The invention has been made in view of these circumstances, and provides a vehicle lamp in which marks are formed on a surface of a front lens made of synthetic resin, a vehicle lamp in which the marks can be formed without sacrificing the appearance of the lamp, and its marking method.
In order to achieve the above result, the lamp according to the invention does not require use of a removable insert, rather the mark is formed with recess groove by laser beam irradiation. The invention thus concerns a vehicle lamp having a front lens made of synthetic resin of which surface is marked with a predetermined mark, wherein the mark is composed of a recess groove formed by irradiating a laser beam on the surface of the front lens to define the shape of the mark.
The term xe2x80x9cvehicle lampxe2x80x9d may be a front lamp or a signal lamp. As long as the xe2x80x9cfront lensxe2x80x9d is made of a synthetic resin and a light-permeable, its material and color are not particularly limited. Further, the front lens may be a lens in which lens elements are formed on its inner surface or a transparent lens.
As long as the above xe2x80x9cpredetermined markxe2x80x9d can be formed by the irradiation of a laser beam, it is not limited to the specific kind of a mark. The above xe2x80x9cirradiation of the laser beam along the shape of the markxe2x80x9d, specifically, may be performed by moving the laser beam by scanning, by moving the front lens, or by any combination of them.
As long as the above xe2x80x9claser beamxe2x80x9d used for irradiation can form a recess groove on the surface of the lens, the type thereof is not particularly limited. For example, a carbon dioxide laser can be used.
As long as the existence of the mark can be recognized by formation of the recess groove, the size and shape of a section of the above xe2x80x9crecess groovexe2x80x9d are not particularly limited.
Under the above constitution, in the vehicle lamp according to the invention, the mark is formed on a surface of the front lens made of synthetic resin. This mark is composed of a recess groove formed by irradiating the laser beam on the surface of the front lens corresponding to the shape of the mark. Therefore, the following advantages can be obtained. First, even in a case in which the mark is different in the displayed content, for example, the lamp certification mark must be formed at the same position of the front lens but with different information, such a mark can be readily formed by suitable performing irradiation control of the laser beam. Such operation prevents the occurrence of an outline of the removable insert that appears on the surface of the front lens when a conventional method such as that of the example in which changes of the mark display content are performed using the removable insert are used.
Accordingly, according to the invention, in a vehicle lamp in which the mark is formed on the surface of the front lens made of synthetic resin, the mark can be formed without deteriorating the appearance of the lamp.
The above xe2x80x9cmarkxe2x80x9d may be formed on either of the inner surface or the outer surface of the front lens. If the mark is formed on the inner surface, dust or wax can be prevented from entering the recess groove, which may occur in the case in which it is formed on the outer surface.
The above recess groove may be single or plural. In the case where plural recess grooves are formed at a predetermined small distance and in parallel, the following advantages can be obtained. In the case that the irradiation energy of the laser beam is set to a large value in some degree, the existence of the mark can be sufficiently recognized even if only a single recess groove is formed. However, in this case, there is concern that smoke may be produced by the irradiation energy of the laser beam when the recess groove is formed. If smoke is produced, particles of smoke may adhere to the surface of the front lens, which could cause a blurring or fogging of the front lens. Therefore, plural recess grooves may be formed at the performed small distance and in parallel with a laser beam with small radiation energy that is too small to produce smoke, and the existence of the mark can still be recognized. Thus, it is possible to prevent particles of smoke from adhering to the surface of the front lens.
Further, since the laser beam irradiation can be performed with small irradiation energy, there is no concern that the color of the recess groove changes into yellow or that foaming is produced in the recess groove. Therefore, the appearance of the lamp can be improved.
The mark formed on the surface of the front lens may have some intersecting points (corner points or junctions). Since the irradiation energy of the laser beam concentrates onto intersecting points, smoke may be produced from the intersecting points. Therefore, if the recess grooves are formed so as to break off at the positions of the intersecting points, it is possible to prevent smoke from being produced from the intersecting points by the laser beam irradiation. Therefore, it is possible to prevent particles of smoke from adhering to the surface of the front lens.
A hard coating film is frequently formed on the outer surface of the front lens to prevent the front lens from being damaged. In case that a mark is formed on the inner surface of the lens, if the laser beam irradiation is performed after the hard coat processing is provided on the lens, it is possible to prevent a jig for supporting the front lens from coming into contact and scratching the outer surface of the front lens because the hard coating film has been formed.
Further, in case that the front lens is made of polycarbonate resin, when a mark is formed on its inner surface, the laser beam irradiation is performed in state where the inner surface of the front lens faces downward. Therefore, even if smoke is produced by the laser beam irradiation energy, since the particles of smoke produced from the polycarbonate resin are heavier than air, the particles descend. Therefore it is possible to prevent smoke particles from adhering to the surface of the front lens.
In case that the mark is formed on the inner surface of the front lens, the following advantages can be obtained by forming an antifogging coating film on the inner surface. First, if an antifogging coating film is formed on the inner surface of the front lens, the existence of the antifogging coating film prevents particles of smoke from adhering to the inner surface of the front lens even when smoke is generated during laser beam irradiation. Owing to this, it is possible to set the irradiation energy of the laser beam to a high value: therefore, it is possible to recognize the existence of a mark even with one recess groove. In this case, the laser beam irradiation is performed after the antifogging coating film is formed on the inner surface of the front lens. If the antifogging coating film is formed after the hard coat processing on the outer surface of the front lens, it is possible to prevent jigs for supporting the front lens from coming into contact and scratching the outer surface of the front lens because the hard coating film has already been formed.
In case that the laser beam irradiation is performed after the antifogging coating film is formed, the antifogging coating film is removed in a portion where the laser beam is irradiated. However, there is no concern that the appearance of the lamp is deteriorated even if particles of smoke do adhere on the removed portion since the portion where the laser beam is irradiated is the portion constituting the mark.